The operating efficiency of light emitting diodes (LEDs) may be improved in a number of ways. These include improvements in the quality of the semiconductor layers and the design of the structure to maximize coupling of light out of the LED.
The operating efficiency of LEDs based on AlGaInN or InGaN decreases as the net drive current is increased as is shown in graph 110 of FIG. 1 for a green GaInN LED. This effect exists in addition to the well-known effect in LEDs where efficiency decreases due to heating brought on by increases in the drive current. The effect limits the performance of AlGaInN or InGaN at high drive currents. Additionally, for AlGaInN or InGaN LEDs, a wavelength shift to shorter wavelengths occurs as the current increases.